1. Field of the Invention
The present invention relates to a self-winding-type of device for raising and lowering various types of fixtures, such as lighting fixtures or public-address speaker systems to be installed above the ground at an outdoor field, above the floor in a room, or on the ceiling of a room.
2. Related Prior Art
Up to now, when various types of fixtures such as streetlights are to be installed at a raised position, or when such fixtures that have been installed at a raised position require maintenance, generally one of the following three procedures is used: (1) a scaffold is provided; (2) a vehicle designed for working at an elevated position is used; or (3) a lift for maintenance work at a raised position is provided.
In the case of a fluorescent-lighting fixture that is installed on a ceiling, for example, a bracket member on the fluorescent-lighting fixture is fixed at the desired position on the ceiling by a fitting means such as fitting screws, and then the main body of the fluorescent-lighting fixture is secured to the bracket member by such fitting means.
However, in such fitting procedures as described above, it is necessary for the fixture to be lifted to an elevated position, and for one or more workers to get to that elevated position by using a raised-position working vehicle. Especially when a lifting device for maintenance work is installed according to the procedure as in item (3) above, there is a problem that, if the lift device itself experiences any trouble or malfunction, it is necessary to build a scaffold as in item (1) or to use an elevated-position work vehicle as in item (2).
Therefore, it is a primary object of the present invention to provide a self-winding-type lifting device that can simplify the work of installing fixtures at an elevated position, and that also makes it possible to carry out maintenance work on such a fixture at a low position by lowering the fixture.
The present invention provides for a self-winding-type fixture-lifting/lowering device to be used for installing fixtures at an elevated position and to be movable upward and downward, with said device comprising:
(1) a secure block securely fitted to the elevated position;
(2) a lifting/lowering block that (a) hangs from said secure block by a pair of wire cables in a manner so as to be movable upward and downward, that supports the aforementioned fixture, and (b) carries a pair of winding drums for winding and unwinding, respectively, the wire cables referred to below, an electric motor for driving the winding drums synchronously with each other, and a battery for supplying electric power to said electric motor;
such that each of said wire cables is secured to the lifting/lowering block at one end and connected to the winding drums and arranged so as to pass through a path formed on (a) a first pulley that is fixed to the secure block, (b) a second pulley that is disposed apart from the first pulley and fixed to the secure block, and (c) a third pulley that is fixed to the lifting/lowering block;
(3) a lock mechanism for locking the lifting/lowering block against the secure block at the uppermost position thereof; and
(4) a release mechanism to release the lock mechanism when the lifting/lowering block is to be moved downwards.
Preferably, the secure block comprises an upper framework of substantially rectangular shape, and the lifting/lowering block comprises a lower framework of substantially rectangular shape, with (a) one end of each of the aforementioned wire cables being secured at a fixing spot disposed at a corner portion of the lower framework, (b) each of the third pulleys being positioned apart from the fixing spot in the widthwise direction of the lower framework, and (c) the first and second pulleys being positioned at points corresponding to the fixing spot and the third pulleys.
The electric motor can be one that can rotate in the direction designed to wind the wire cables when electric power is supplied, and that can rotate in the reverse direction when electric power is not supplied.
Furthermore, the self-winding-type fixture-lifting/lowering device can include a reduction mechanism inserted between the driving shaft of the electric motor and the winding drums.
Preferably, the lock mechanism comprises at least (1) one engaging member that is fixed to the secure block so as to be swingable around a substantially horizontal axis and urged to rotate toward one end of the movable range thereof, and that has at least one engaging hole, (2) at least one hook member to be engaged with the engaging hole of the engaging member and fixed to the lifting/lowering block, and (3) a lock-releasing mechanism for releasing the engagement between the engaging member and the hook member by rotating the engaging member.
Alternatively, the lock-releasing mechanism comprises a lever that is swingably fixed to the secure block and that disengages the locking member from the hook-member engaging member by rotating the engaging member manually.
Another preferable lock-releasing mechanism comprises a solenoid-plunger mechanism for disengaging the engaging member from the hook member when said solenoid-plunger mechanism is supplied with electricity.
A further lock-releasing mechanism can comprise a spring member made of a shape-memory alloy that normally keeps the engaging member in the locked position, and that releases the engaging member from the locked position when said spring member is heated above a specified temperature.
With the present invention, the fixture to be installed at an elevated position can be either a chandelier or a lighting fixture that is to be installed on the ceiling.
Examples of the types of fixtures to be installed at an elevated position by the self-winding-type fixture-lifting/lowering device of the present invention include box-type lighting fixtures, ball-type lighting fixtures, and traffic-signal devices.
In this specification, the term xe2x80x9celevated positionxe2x80x9d is used to mean a position above the height that the hands of a typical worker standing on the floor can reach. For example, such an elevated position can be the ceiling of a room; the upper part of the inside or outside wall of an ordinary building, a large-size building such as a dome-type space, or an arena; a multipurpose hall; or the upper part of a street light pole or of a tower of various typesxe2x80x94on all of which it is very difficult or not easy to install fixtures or to conduct maintenance thereon.
The self-winding-type fixture-lifting/lowering device of the present invention is suitable especially for installing fixtures or the components thereof, such as the lamps used in lighting fixtures, because the lamps used in such applications have a relatively short working life and it is necessary to change broken or worn-out lamps relatively frequently. However, the self-winding-type fixture-lifting/lowering device of the present invention can be applied to every type of fixture that is installed at an elevated position, and it offers such benefits as the fact that maintenance work can be performed on such fixtures easily and safely. Examples of fixtures other then lighting fixtures include public-address speaker systems, monitoring cameras, and image monitors. That is, the present invention is not limited to installing only elevated-position light fixtures.